Blasting cartridge



2 Sheets-Sheet l July 28, 1931'. F. H. KNEELAND BLASTING CARTRIDGE Filed Oct. 26. 1929 :W k m .1 m-

Patented July 28, 1931 UNITED STATES PATENT OFFICE FRANK H. KNEELAND, OF CHICAGO, ILLINOIS, ASSIGNOR TO SAFETY MINING 0.0M- PANY, OF (.IHIG'AGO, ILLINOIS, A CORPORATION BLASTING CARTRIDGE Application filed October 26, 1929. Serial No. 402,619.

The present invention relates to blasting cartridges of the type comprising a metallic casing having a gas chamber formed therein for the reception of a compressed gas charge and an electrically energizable heater unit therein for causing expansion of the charge.

More particularly, theinvention is concerned with an improved and'greatly simplified method and means whereby the heater unit may be connected with a source of electricity.

The principal object of the invention is to simplify blasting cartridges of the type re- Figure 4 is a view in longitudinal section illustrating a modified form of iny invention, Figure 5 is a transverse section on line 5-'5 of Figure 4, and

Figure 6 1s a detail view *ofthe' contact ring insulating of Figure 4.

' drical metallic casing l'having an internal ports Q The invention is herein represented in a blasting cartridge which consists of a cylingas chamber. 2, the open end of which is closed by a pressure responsive rupturable disc 3. A shear ring 4 is positioned adjacent the disc 3 and is secured in such position --by -means of a dischar e cap 5 which may be screw threaded or 0t erwise adjustably connected with the end of the cartridge. A cap 5 is provided with a plurality of discharge 6. The cartridge thus formed is designed to be charged with a compressed gas. and isprovided with a suitable heat producing unit8 by means of which the pressure of the gas 1s increased to such a point as to cause rupture of the disc 3.

In cartridges of this type the heat producing unit 8 is usually designed to be energized by the passage of an electric current therethrough and for this purpose it has heretofore been proposed to provide an electrode extending through the body of the cartridge and insulated therefrom whereby to provide a circuit including the electrode, the heater,

and the metallic body of the cartridge. The present invention is concerned with an improvement in the method and means of providing a circuit for an electrically energizable heater unit. According to the present invention, this is accomplished by insulating the discharge assembly from the body of the cartridge and arranging the heater in such a way that its terminals contact with an element of the discharge assembly and with the cartridge body respectively. Thus, the rupturable disc 3 and shear ring 4 may be regarded as the discharge assembly and in the form of the invention shown in Figure 1 these elements are completely insulated from the body of the cartridge by means of an insulating member 7, the exact form of which is more clearly illustrated in detail in Figure 8. In the construction shown in Figure 1 the insulating member 7 is extended outwardly to the end of the cartridge and is formed with.

screw threads corresponding to the threads formed internally'of the cartridge body. The discharge cap 5 is adapted to engage the threads formed in the insulating member 7 and to be threaded into the cartridge to the point where its inner end is in engagement with the shear ring. Thus, the discharge cap 5, as well as the discharge assembly 3 and 4, is effectively insulated from the cartridge body. With the construction described the two poles ofa source of electricity may be connected to the discharge cap or any portion of the discharge assembly and to the car- 'tridge body as indicated at 11 and 12 respectively in order to provide a circuit for the heater unit 8 which has its contacts in engagement with the cartridge body and metallic disc 3-respectively.

In the modified construction shown Figure 4, the discharge cap 5 is not insulated from the body of the cartridge, but the memher 7 serves. to insulate the discharge assembly consisting of the disc 3 and shear ring 4 with respect to the body of the cartridge. Thus, in order to complete a circuit through the heater it is necessary that one connection be made to the discharge assembly and for this purpose a metallic ring is positioned adjacent the shear ring 4. This ring 10'is suitably insulated from the discharge cap 5 10 by meansof an insulating ring 9. Connection may be made to a lug 11 formed on the ring 10. The body of the cartridge is provided with one or more apertures 12 throu h which a wire may be passed to provide t e 15 other connection for the circuit.

In view of the foregoing description, it should be appreciated that the present invention obviates the necessity of usin a separate electrode extending throu h an insulated 29 from the body of the cartridge. By the present invention the necessary elements of the discharge assembly are made to serve the purpose of the electrode and the cartridge construction is thereby considerably simplified.

I claim:

1. A blasting cartridge comprising a metallic body having a discharge opening, a discharge assembly associated therewith and 50 insulated from said body, and an electrically energizable heater unit having contacts engaging said body and discharge assembly respectively. V

2. A blasting cartridge comprising a metallic body having a discharge opening, a rupturable metallic closure for said opening. means for insulating said closure from said body, and an electrically energizable heater having contacts engaging said body and clo- 10 sure respectively.

3. A blasting cartridge comprising a metallic body having a discharge opening, a metallic closure for said opening, means for insulating said closure from said body, an' electrically energizable heater having contacts engaging said body and closure respectively, and means in electrical connection with said closure adapted for connection'with one pole of a source of electricity and means for coni0 necting the other pole of said source of electricity to said bod Q 4. A blasting cartrid e comprising a metallic casing having a ischarge opening, a rupturable closure for said opening, a dis- F5 charge cap having adjustable connection with said casing and cooperating with said closure to maintain the same in sealed relation with said opening, and means for insulating said closure from said casing and discharge ca 0 whereby it is adapted to serve as an electrode for conducting electricity to the interior of saisd casing. C

igned at hica 0 Illinois this 17th da of October, 1929. g 5 FRANK H. KNEELAND. 

